[Changes in electrical capacitance of silicone rubber impression materials during setting process (author's transl)].

Abstract

Since the silicone rubber impression materials have the high dielectrics, the changes in electrical capacitance during its setting process were measured. The time coordinate of the point of inflexion in the curve of percent changes in its electrical capacitance V.S. time at the setting process were compared with setting time in mechanical measurement. The results were summerized as follows. 1) The degree of advancement of the setting reaction in silicone rubber impression materials were able to be observed by measuring its electrical capacitance. 2) Since the change of the electrical capacitance measured here is corresponding to the setting process of the silicone rubber impression material in this system, the point of inflexion of the curve of the reduced electrical capacitance is the indication of the setting process. 3) The time which demands to reach to this point of inflexion highly corresponds to the setting time of the same material by the mechanical measurements. 4) It is possible to determine the setting time of the silicone rubber impression material by means of measuring the changes in its electrical capacitance.